Liquid pump

ABSTRACT

A cover end of a fuel pump is formed by resin molding and has a tubular portion, which holds a bearing that is placed along a central axis of the tubular portion and rotatably supports one end portion of a shaft of a motor arrangement. Furthermore, three terminals, which supply three-phase electric power received from an outside to windings on a phase-by-phase basis, are insert molded in the cover end. In the cover end, a first transverse passage, which is formed between the first terminal and the second terminal in a circumferential direction, and a second transverse passage, which is formed between the second terminal and the third terminal in the circumferential direction, are configured into a form of V-shape, which diverges in a radially outer direction, in a view taken in an axial direction.

CROSS REFERENCE TO RELATED APPLICATION

This application is the U.S. national phase if International ApplicationNo. PCT/JP2014/004529 filed on Sep. 3, 2014 and is based on andincorporates herein by reference Japanese Patent Application No.2013-191594 filed on Sep. 17, 2013.

TECHNICAL FIELD

The present disclosure relates to a liquid pump.

BACKGROUND ART

Previously, a liquid pump, which rotates a rotatable member, such animpeller, by a motor arrangement received in an inside of the liquidpump to pump liquid, is known. In general, in the liquid pump having theabove-described motor arrangement, the liquid, which is drawn through asuction port formed at one axial end of the liquid pump, is pressurizedand is discharged to an outside through a discharge port formed at theother axial end of the liquid pump.

A discharge conduit, which forms the discharge port, is formedintegrally with a cover end made of resin in such a manner that thedischarge conduit projects from the axial end portion of the liquidpump. A tubular portion, which holds a bearing that rotatably supportsone end portion of a shaft of the motor arrangement, is formed in aninside of the cover end along a central axis of the cover end.Furthermore, an end portion of a stator of the motor arrangement,specifically, a stator winding portion, and winding connections forconnecting with windings are molded with resin for the purpose ofelectrical insulation.

For example, in a fuel supply pump recited in the Patent Literature 1,the winding portion, a dielectric molded portion of the winding portion,and the cover end located at the discharge port side end portion of thefuel supply pump in the axial direction are formed integrally with theresin. Communication passages, each of which communicates between aradially inner side of the cover end and a radially outer side of thecover end, are formed. The fuel, which is pumped from the pumparrangement, flows from a second fuel supply passage, which is formedbetween an outer peripheral portion of the stator core and an innerperipheral portion of a housing, into a fuel merging portion located onthe radially inner side through the communication passages.

In the construction of the Patent Literature 1, circumferential portionsof the cover end, which are other than the communication passages,become thick wall portions made of the molded resin. In general, thethick wall portion accumulates the greater amount of heat in comparisonto a thin wall portion at the time of resin molding to cause generationof a sink mark and/or deformation due to localized shrinkage of theresin material. Particularly, when the sink mark and/or the deformationis formed in the tubular portion, which holds the bearing that rotatablysupports the one end portion of the shaft, it will cause deviation ofthe central axis of the shaft or tilt of the central axis of the shaftat the time of installing the shaft. Thereby, required axis accuracy ofthe shaft, such as required coaxiality or required perpendicularity ofthe shaft, cannot be ensured. As a result, the operational performanceor the durability of the motor arrangement may possibly be adverselyinfluenced.

CITATION LIST Patent Literature

Patent Literature 1: JP2010-63344A (corresponding to US2010/0034674A1)

SUMMARY OF INVENTION

The present disclosure is made in view of the above point. It is anobjective of the present disclosure to provide a liquid pump, in whichone end portion of a stator and a cover are integrally resin molded,while required axis accuracy of a motor arrangement is ensured.

A liquid pump of the present disclosure includes a motor arrangement, ahousing, a cover end and a pump arrangement.

The motor arrangement has: a stator, in which a plurality of windings iswound around cores; and a rotor, which includes a plurality of magneticpoles and is rotated about a rotational axis of a shaft by a magneticfield generated at the stator.

The housing, which is configured into a tubular form, receives thestator and the rotor. A plurality of outer passages, each of whichpasses between an inner wall of the housing and an outer wall of thestator and extends through the motor arrangement in an axial direction,is formed in the housing.

The cover end is resin molded integrally with one end portion of thestator on one axial side of the motor arrangement and closes an openingof the housing. A tubular portion, which holds a bearing that rotatablysupports one end portion of the shaft, is formed along a central axis ata side of the cover end where the motor arrangement is located. Adischarge conduit, which has a discharge passage in an inside of thedischarge conduit, is formed at an opposite side of the cover end, whichis opposite from the motor arrangement. A first terminal, a secondterminal and a third terminal, which supply three-phase electric powerreceived from an outside to the plurality of windings on aphase-by-phase basis, are insert molded in the cover end.

The pump arrangement includes a rotatable member, which is rotatedtogether with the rotor on another axial side of the motor arrangementto pump liquid.

The first terminal, the second terminal and the third terminal arearranged one after another in this order at predetermined intervals in acircumferential direction on an opposite side of an imaginary plane thatincludes the central axis of the cover end. The opposite side of theimaginary plane is opposite from another side of the imaginary planewhere the discharge conduit is formed.

The cover end includes a plurality of transverse passages, which areformed by a plurality of slide mold parts, while each of the pluralityof transverse passages radially communicates a corresponding one of theplurality of outer passages to an inner passage, which is formed aroundthe tubular portion and is communicated with the discharge passage.

The plurality of transverse passages includes a first transversepassage, which is formed between the first terminal and the secondterminal in the circumferential direction, and a second transversepassage, which is formed between the second terminal and the thirdterminal in the circumferential direction, while the first transversepassage and the second transverse passage are configured into a form ofV-shape, which diverges in a radially outer direction, in a view takenin the axial direction.

As a countermeasure that reduces the press mark and the deformationcaused by the thick wall portion at the time of molding, it is effectiveto divide the thick wall portion by forming the first transverse passageand the second transverse passage. However, if the first transversepassage and the second transverse passage are formed to be parallel toeach other, the volume of the resin portion, which is located betweenthe first transverse passage and the second transverse passage and hasthe second terminal embedded therein, cannot be made small.

When the first transverse passage and the second transverse passage areconfigured into the form of V-shape, which diverges in the radiallyouter direction, in the view taken in the axial direction, the volume ofthe resin portion, in which the second terminal is embedded, can beminimized. Thus, it is possible to limit the deterioration of thecoaxiality or the perpendicularity of the tubular portion caused by thesink mark and/or the deformation at the molding time, and thereby it ispossible to ensure the appropriate axis accuracy of the motorarrangement.

The windings of the stator are wound around the six cores, which areequally divided in the circumferential direction. In such a case, whenthe first terminal, the second terminal and the third terminal arearranged one after another at 60 degree intervals, the positionalrelationship between each of the terminals and the cores can be equallyset in good balance. Here, the angle of 60 degrees refers to an angle ina range that can be recognized as 60 degrees in view of the technicalcommon sense in the technical field of the present disclosure, andthereby the angle of 60 degrees is not limited to the exact angle of 60degrees.

Furthermore, when the first terminal, the second terminal and the thirdterminal are respectively made of the identical members, which areidentical to each other, a reduction in the number of steps undercontrol and an improvement in the efficiency of the assembling operationcan be achieved.

Furthermore, in a mold, which is used to mold the cover end, a moldopening direction of the mold is the axial direction, and the transversepassages, each of which extends in a corresponding direction that isperpendicular to the axial direction, are formed by slide mold parts,each of which moves in a direction of a corresponding parting line. Inthis case, when the first transverse passage and the second transversepassage are formed to be perpendicular to each other, the structure ofthe slide mold parts can be simplified. Here, the term “perpendicular”refers to the state of perpendicularity with an achievable accuracy thatis achievable in the resin molding and thereby the term “perpendicular”does not necessarily refers to the exact angle of 90 degrees.

The principle of the present disclosure with respect to the liquid pumpdiscussed above is applicable to a fuel pump that pumps fuel (fuel asliquid), which is drawn from a fuel tank. For example, a fuel pump for avehicle is required to have a high quality to continuously implement astable performance of the fuel pump. When the fuel pump of the presentdisclosure is applied, it is possible to ensure the appropriate axisaccuracy of the motor arrangement. Thereby, it is possible to stabilizethe pump performance that is achieved with the rotatable member, whichis rotated by the motor arrangement.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an axial cross-sectional view of a fuel pump according to anembodiment of the present disclosure, indicating a cross section takenalong line I-I in FIG. 4.

FIG. 2 is an axial cross-sectional view of the fuel pump according tothe embodiment of the present disclosure, indicating a cross sectiontaken along line II-II in FIG. 4.

FIG. 3 is a plan view taken in a direction of an arrow III in FIGS. 1and 2.

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1.

FIG. 5 is a cross-sectional view of a fuel pump of a comparativeexample, corresponding to FIG. 4.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present disclosure will be describedwith reference to the accompanying drawings.

A fuel pump, which serves as a liquid pump, according to the embodimentof the present disclosure will be described with reference to FIGS. 1 to4.

The fuel pump 1 draws fuel of a fuel tank (not shown) through a suctionport 71 and discharges the drawn fuel from a discharge port 79, which isan opening of a discharge conduit 28, to an internal combustion engine.The fuel pump 1 includes a motor arrangement 50 and a pump arrangement60. An outer shell of the fuel pump 1 includes a housing 15, a cover end20 and a pump cover 61. In the following description of the fuel pump 1,the upper side of FIGS. 1 and 2 will be referred to as a discharge port79 side, and the lower side of FIGS. 1 and 2 will be referred to as asuction port 71 side.

The housing 15 is configured into a cylindrical tubular form and is madeof metal (e.g., iron).

The cover end 20 is molded from a resin material, such as PPS(polyphenylene sulfide), which is resistant to the fuel. The cover end20 is molded integrally with one end portion of a stator 11 at thedischarge port 79 side of the motor arrangement 50 in the axialdirection. That is, the one end portion of the stator 11 is insertmolded in the cover end 20. The cover end 20 closes an opening of thehousing 15, which is located on the side where the discharge port 79 isplaced. A tubular portion 27, which holds a bearing 55 that rotatablysupports one end portion of a shaft 54, is formed in an inside of thecover end 20, i.e., is formed along a central axis O of the motorarrangement 50 at a side of the cover end 20 where the motor arrangement50 is located. In the present embodiment, the central axis O of thecover end 20 also serves as a rotational axis of the shaft 54.

The discharge conduit 28 is formed integrally with an outer side of thecover end 20, specifically, is formed integrally with an opposite sideof the cover end 20, which is opposite from the motor arrangement 50, atone side (a right side in FIG. 3) of a reference plane S (see FIGS. 3and 4), which is an imaginary plane that includes the central axis O ofthe cover end. Furthermore, at the other side (a left side in FIG. 3) ofthe reference plane S, three terminals, i.e., a first terminal 31, asecond terminal 32 and a third terminal 33 are insert molded in thecover end 20, and a connector 29 projects from and is formed integrallywith the cover end 20. That is, the discharge conduit 28, the connector29 and the terminals 31, 32, 33 are placed in a manner that avoids aninterference therebetween.

The discharge conduit 28 has a discharge passage 78 in an inside of thedischarge conduit 28, and another conduit, which conducts the dischargedfuel to a downstream side, is connected to the discharge conduit 28.

An electric power cable, which extends from an external drive device, isconnected to the first terminal 31, the second terminal 32 and the thirdterminal 33, and the first terminal 31, the second terminal 32 and thethird terminal 33 supply three-phase electric power to a plurality ofwindings 13 of the motor arrangement 50. For example, the first terminal31, the second terminal 32 and the third terminal 33 correspond to, forexample, a U-phase, a V-phase and a W-phase, respectively. However, thearrangement of the U-phase, the V-phase and the W-phase is not limitedto this arrangement.

Furthermore, in the present embodiment, the three terminals 31, 32, 33are arranged one after another at 60 degree intervals about the centralaxis O of the cover end 20 in response to the presence of six cores 12of the stator 11, which will be described later and are arranged oneafter another in a circumferential direction.

Furthermore, in the present embodiment, the three terminals 31, 32, 33are respectively made of identical members, which are identical to eachother.

When the discharge port 79 side end portion of the housing 15 isradially inwardly crimped against the cover end 20, the cover end 20 isfixed at the inside of the housing 15. Thereby, removal of the cover end20 from the housing 15 in the axial direction is limited.

As shown in FIG. 4, in the state where the cover end is inserted intothe housing 15, parts of the outer peripheral portion of the cover end20 contact the inner wall of the housing 15. Thereby, the cover end 20is held coaxially with the housing 15. Other parts of the cover end 20,which do not contact the inner wall of the housing 15, form transversepassages 41-46, each of which radially communicates a corresponding oneof a plurality of outer passages 47 to an inner passage 48.

Each of the outer passages 47 is a passage that is placed between theinner wall of the housing 15 and the outer wall of the stator 11 of themotor arrangement 50 and axially extends through the motor arrangement50. The inner passage 48 is a passage that is formed around the tubularportion 27 and communicates with the discharge passage 78. Specifically,the inner passage 48 is an annular passage that is located on a radiallyouter side of the tubular portion 27 and circumferentially extends allaround the tubular portion 27. Details of the transverse passages 41-46will be described later.

Next, the structure of the motor arrangement 50 will be schematicallydescribed. The motor arrangement 50 is a brushless motor that includesthe stator 11, a rotor 51 and the shaft 54.

The stator 11 is received in the inside of the housing 15. In thisstate, the multiple outer passages 47 are formed between the outer wallof the stator 11 and the inner wall of the housing 15 at predeterminedcircumferential parts.

The stator 11 includes the six cores 12, which are made of a magneticmaterial, such as iron, and around which the windings 13 are wound.These six cores 12 are joined one after another in the circumferentialdirection and form the cylindrical tubular body. That is, each one ofthe cores 12 corresponds to a part that has a central angle of 60degrees. Surfaces of the cores 12, around which the windings 13 arewound, are resin molded for the purpose of electric insulation. Incontrast, inner wall surfaces of the cores 12, which are opposed to therotor 51, are not resin molded, so that metal surfaces are exposed atthe inner wall surfaces of the cores 12.

At the end portion of the stator 11 where the cover end 20 is placed,the cores 12 of the same phase are electrically connected, and eachcorresponding core 12 and the corresponding terminal 31, 32, 33 areelectrically connected with each other. The electrical connections ofthe winding portion and the windings 13 are molded with the resin forthe purpose of the electric insulation. In the present embodiment, thecover end 20 is integrally molded in this resin molding process. Thatis, a stator subassembly, around which the windings 13 are wound and inwhich the terminals 31, 32, 33 are connected to the windings 13, isinserted into a mold, and thereafter the cover end 20 is resin molded inthe mold. In this way, as shown in FIGS. 1 and 2, the cover end 20 isresin molded integrally with the one end portion of the stator 11.

The rotor 51 is rotatably received on the inner side of the stator 11.In the present embodiment, a radial gap between the rotor 51 and thestator 11 is set to a relatively small size.

The rotor 51 includes an inner core 52, which is made of a magneticmaterial and is placed at the inner side of the rotor 51, and a magnet53, which is placed around the inner core 52 and forms a plurality ofmagnetic poles. In the magnet 53, the N-poles and the S-poles arealternately arranged one after another in the circumferential direction.The present disclosure is not limited to the above structure, in whichthe magnet 53 is formed separately from the inner core 52. For example,the core made of the magnetic material may be magnetized to form aplurality of magnetic poles.

The shaft 54 is securely press fitted into a hole that is formed in theinner core 52 of the rotor 51 along the central axis of the inner core52. Two end portions of the shaft 54 are rotatably supported by thebearing 55, which is placed at the discharge port 79 side, and a bearing56, which is placed at the suction port 71 side.

When the three-phase electric power is supplied to the windings 13through the terminals 31, 32, 33, a rotating magnetic field is generatedat the stator 11. Thereby, the rotor 51 is rotated together with theshaft 54.

Next, the structure of the pump arrangement 60 will be schematicallydescribed. The pump arrangement 60 includes the pump cover 61, a pumpcasing 62 and an impeller 65.

The pump cover 61 has the suction port 71, which is configured into atubular form and opens at the lower side of FIG. 1, and the pump cover61 closes the suction port 71 side end portion of the housing 15. Whenthe suction port 71 side end portion of the housing 15 is radiallyinwardly crimped against the pump cover 61, the pump cover 61 is fixedat the inside of the housing 15. Thereby, removal of the pump cover 61from the housing 15 in the axial direction is limited.

The pump casing 62 is configured into a circular plate form and isplaced at a location between the motor arrangement 50 and the pump cover61. A through hole 63 is formed at a center part of the pump casing 62such that the through hole 63 extends through the pump casing 62 in aplate thickness direction of the pump casing 62. The suction port 71side bearing 56 is fitted into the hole 63 of the pump casing 62. Thebearing 56 cooperates with the discharge port 79 side bearing 55 torotatably support the two end portions of the shaft 54.

The impeller 65, which serves as a rotatable member, is made of resinand is configured into a generally circular plate form. The impeller 65is received in a pump chamber 64, which is formed between the pump cover61 and the pump casing 62. An outer wall of the pump chamber 64 side endportion of the shaft 54 is partially cut to have a D-shape and is fittedinto a hole 66, which is formed at a center part of the impeller 65 andis configured into a corresponding D shape. In this way, the impeller 65is rotated in the pump chamber 64 through the rotation of the shaft 54.

An inlet guide groove 72, into which the fuel is guided from the suctionport 71, is formed in the impeller 65 side surface of the pump cover 61.An outlet guide groove 73 is formed in the impeller 65 side surface ofthe pump casing 62. The outlet guide groove 73 is communicated with apassage 74, which extends through the pump casing 62 in a platethickness direction of the pump casing 62. The impeller 65 includesblades 67 at a location which corresponds to the inlet guide groove 72and the outlet guide groove 73.

When the impeller 65 is rotated along with the rotor 51 and the shaft 54upon energization of the windings 13 of the motor arrangement 50, thefuel at the outside of the fuel pump 1 is guided into the inlet guidegroove 72 through the suction port 71. The fuel, which is guided to theinlet guide groove 72, is pressurized through the rotation of theimpeller 65 and is guided to the outlet guide groove 73. The pressurizedfuel flows through the passage 74 and is guided to an intermediatechamber 75, which is formed on the motor arrangement 50 side of the pumpcasing 62.

In the present embodiment, the radial gap located between the rotor 51and the stator 11 does not form the fuel passage. Therefore, the fuel inthe intermediate chamber 75 flows through the motor arrangement 50 viathe outer passages 47. Then, the fuel enters the inner passage 48through the transverse passages 41-46 shown in FIG. 4 and reaches thedischarge passage 78. Thereafter, the fuel is discharged from thedischarge port 79.

Next, the construction of the transverse passages, which form thecharacteristic feature of the present embodiment, will be described withreference to FIGS. 4 and 5 and in comparison with a comparative example.

As shown in FIG. 4, in the fuel pump 10 of the present embodiment, thecover end 20 is molded to form the six transverse passages 41-46 throughuse of slide mold parts SL1-SL4. Each of the transverse passages 41-46communicates the corresponding one of the outer passages 47, which boundwith the inner wall of the housing 15, to the inner passage 48, which isformed around the tubular portion 27 and is communicated with thedischarge passage 78.

Specifically, the first transverse passage 41 is formed by using theslide mold part SL1 at a location between a resin portion 21, in whichthe first terminal 31 is embedded, and a resin portion 22, in which thesecond terminal 32 is embedded. The second transverse passage 42 isformed by using the slide mold part SL2 at a location between the resinportion 22, in which the second terminal 32 is embedded, and a resinportion 23, in which the third terminal 33 is embedded.

The first transverse passage 41 and the second transverse passage 42 areconfigured into a form of V-shape, which diverges in a radially outerdirection, in a view taken in the axial direction. Particularly, in thepresent embodiment, a crossing angle of this form of V-shape is 90degrees, so that the first transverse passage 41 and the secondtransverse passage 42 are perpendicular to each other. That is, theslide mold part SL1 and the slide mold part SL2 are respectively movedin the two direction, which are perpendicular to each other, to form theabove-described configuration. A side surface (a planar surface) 22 a ofthe resin portion 22, which is adjacent to the first transverse passage41, and a side surface (a planar surface) 22 b of the resin portion 22,which is adjacent to the second transverse passage 42, are perpendicularto each other.

In FIG. 4, the moving direction of the slide mold part SL1 and themoving direction of the slide mold part SL2 are indicated to be tiltedabout 45 degrees relative to the reference plane S. Here, it should benoted that this tilt angle is not required to be exactly 45 degrees.

Resin portions 24, 26, each of which radially extends, and a resinportion 25, which is in a form of an island placed on an opposite sideof the resin portion 22, are formed on the opposite side of thereference plane S, which is opposite from the terminals 31, 32, 33. Thetransverse passage 43, which is located between the resin portion 23 andthe resin portion 24, and the transverse passage 44, which is locatedbetween the resin portion 24 and the resin portion 25, are formed byusing the slide mold part SL3, which is moved in a moving direction thatis opposite from the moving direction of the slide mold part SL1. Thetransverse passage 45, which is located between the resin portion 25 andthe resin portion 26, and the transverse passage 46, which is locatedbetween the resin portion 26 and the resin portion 21, are formed byusing the slide mold part SL4, which is moved in a moving direction thatis opposite from the moving direction of the slide mold part SL2.

The slide mold parts SL1-SL4 have a known structure that is operatedsynchronously with a mold opening operation through use of an angularpin in the resin molding mold. Alternatively, the slide mold partsSL1-SL4 may have a structure that is operated independently from themold opening operation through use of an actuator, such as an aircylinder or a hydraulic cylinder.

A fuel pump of a comparative example, which is comparative to thepresent embodiment, will now be described with reference to FIG. 5,which indicates a cross section of the fuel pump taken at the same axialposition as that of FIG. 4. The fuel pump 19 of the comparative examplediffers from the present embodiment only with respect to the structureof the transverse passages. In the following description of thecomparative example, similar components, which are similar to those ofthe present embodiment, will be indicated by the same reference numeralsand will not be described redundantly for the sake of simplicity.

As shown in FIG. 5, in the fuel pump 19 of the comparative example, thecover end 80 is molded such that each of slide mold parts SL5-SL8, whichform five transverse passages 91-95, is moved in a correspondingdirection, which is parallel to the reference plane S, or acorresponding direction, which is perpendicular to the reference planeS. Each of the transverse passages 91-95 communicates a correspondingone of the outer passages 47 to the inner passage 48.

Specifically, the first transverse passage 91 is formed between a resinportion 81, in which the first terminal 31 is embedded, and a resinportion 82, in which the second terminal 32 is embedded, and the secondtransverse passage 92 is formed between the resin portion 82, in whichthe second terminal 32 is embedded, and a resin portion 83, in which thethird terminal 33 is embedded. The first transverse passage 91 and thesecond transverse passage 92 are parallel to each other and are formedby using the slide mold part SL5, which is moved in the direction thatis perpendicular to the reference plane S.

The resin portions 84, 85, each of which is configured into a form ofgenerally V-shape, are formed on the side of the reference plane S,which is opposite from the terminals 31, 32, 33. The transverse passage93, which is located between the resin portion 83 and the resin portion84, and the transverse passage 95, which is located between the resinportion 85 and the resin portion 81, are formed by using the slide moldpart SL6 and the slide mold part SL8, respectively. The slide mold partSL6 and the slide mold part SL8 are operated in two directions,respectively, which are parallel to the reference plane S and areopposite to each other. The transverse passage 94, which is locatedbetween the resin portion 84 and the resin portion 85, is formed byusing the slide mold part SL7, which is moved in a direction that isperpendicular to the reference plane S and is opposite from the movingdirection of the slide mold part SL5.

In the comparative example of the above construction, a volume of aportion Y, which is located on a radially inner side of the secondterminal 32 in the resin portion 82, cannot be sufficiently reduced.Therefore, the portion Y may become a thick wall portion, and therebythe portion Y may more easily accumulate the heat in comparison to theother thin wall portion(s) at the time of molding. Thereby, a sink markand/or deformation may possibly be generated due to localized shrinkageof the resin material.

Furthermore, in the thick wall portion, gas, which is generated from thehot resin, may not be released to the outside from the thick wallportion and thereby form a void in many cases. The void may possiblyresult in the shortage of the strength or the deterioration of theappearance. Besides these disadvantages, it is conceivable to have amechanism of that the void causes shrinkage of the resin in such amanner that the resin is pulled into the void to cause generation of thesink mark in the resin or the deformation of the resin.

The sink mark and/or the deformation of the resin may possibly haven aninfluence on the positional accuracy of the bearing 55, which is held bythe tubular portion 27. Specifically, when the positional accuracy ofthe bearing 55 is deteriorated, deviation of the central axis of theshaft 54 or tilt of the central axis of the shaft 54 may occur at thetime of installing the shaft 54. When this occurs, the required axisaccuracy of the shaft 54, such as the required coaxiality or therequired perpendicularity of the shaft 54, cannot be ensured. Therefore,the operational performance or the durability of the motor arrangement50 may be adversely influenced.

In contrast, according to the present embodiment, the first transversepassage 41 and the second transverse passage 42 are configured into theform of V-shape, which diverges in the radially outer direction, in theview taken in the axial direction. A volume of a portion X, which islocated on the radially inner side of the second terminal 32 in theresin portion 22, is substantially reduced in comparison to the volumeof the portion Y of the comparative example. Therefore, by eliminatingthe thick wall portion, it is possible to limit the deterioration of thecoaxiality or the perpendicularity of the tubular portion 27 caused bythe sink mark and/or the deformation at the molding time, and thereby itis possible to ensure the appropriate axis accuracy of the motorarrangement 50.

Furthermore, in the present embodiment, the three terminals 31, 32, 33are arranged one after another at 60 degree intervals about the axis ofthe cover end 20. Therefore, the positional relationship of each of theterminals 31, 32, 33 relative to the cores 12 can be equally set in goodbalance.

In addition, the three terminals 31, 32, 33 are respectively made of theidentical members, which are identical to each other. Therefore, the useof the common parts allows a reduction in the number of steps undercontrol and an improvement in the efficiency of the assemblingoperation.

In addition, in the present embodiment, the first transverse passage 41and the second transverse passage 42 are perpendicular to each other.That is, the moving direction of the slide mold part SL1 and the movingdirection of the slide mold part SL2 can be set to be perpendicular toeach other. Therefore, for example, the slide mold part SL1 can be setin a vertical direction of the mold, and the slide mold part SL2 can beset in a forward and backward operating direction of the mold. Thereby,the structure of the mold can be simplified.

Other Embodiments

(A) The angular intervals of the three terminals 31, 32, 33 in thecircumferential direction are not limited to 60 degrees, which isindicated as the exemplary angle in the above embodiment. Furthermore,the three terminals 31, 32, 33 may be respectively made of differentmembers, which are formed according to different design specifications,respectively. Furthermore, in a case of another terminal constructionwhere a ground terminal and a neutral point terminal are added to theabove described terminals to have a total of four terminals, the aboveembodiment may be applied to three of the four terminals.

(B) The crossing angle between the first transverse passage 41 and thesecond transverse passage 42 is not limited to 90 degrees, which isindicated as the exemplary crossing angle in the above embodiment. Forexample, in a case of a mold, in which each of slide mold parts isindependently driven by, for example, an air cylinder, the crossingangle can be relatively freely set.

(C) The structure of the cover end 20 of the fuel pump 10, particularlythe structure of the cover end 20 other than the locations of the firsttransverse passage 41 and the second transverse passage 42 is notlimited to the structure of the above embodiment. For example, a checkvalve, which limits backflow of the fuel, may be placed in the dischargepassage 78.

(D) The liquid pump of the present disclosure is not limited to the fuelpump and may be used as a pump for pumping another type of liquid, whichis other than the fuel. For example, in a urea SCR system of an exhaustgas purification technique, the liquid pump of the present disclosuremay be applied as a liquid pump that pumps urea water.

The present disclosure is not limited to the embodiments described aboveand can be implemented in various other embodiments without departingfrom the principle of the present disclosure.

The invention claimed is:
 1. A liquid pump configured to pump a liquid,comprising: a motor arrangement that has: a stator, in which a pluralityof windings is wound around cores; and a rotor, which includes aplurality of magnetic poles and is configured to rotate about arotational axis of a shaft by a magnetic field generated at the stator;a housing that is configured into a tubular form and receives the statorand the rotor, wherein a plurality of outer passages, each of whichpasses between an inner wall of the housing and an outer wall of thestator and extends through the motor arrangement in an axial direction,is formed in the housing; a cover end that is resin molded integrallywith one end portion of the stator on one axial side of the motorarrangement and closes an opening of the housing, wherein: a tubularportion, which holds a bearing that rotatably supports one end portionof the shaft, is formed along a central axis at a side of the cover endwhere the motor arrangement is located; a discharge conduit, which has adischarge passage in an inside of the discharge conduit, is formed at anopposite side of the cover end, which is opposite from the motorarrangement; and a first terminal, a second terminal and a thirdterminal, which are configured to supply three-phase electric powerreceived from an outside to the plurality of windings on aphase-by-phase basis, are respectively insert molded in a first resinportion, a second resin portion and a third resin portion of the coverend to seal the first terminal, the second terminal and the thirdterminal from the liquid; and a pump arrangement that includes arotatable member, which is configured to rotate together with the rotoron another axial side of the motor arrangement to pump the liquid,wherein: the first terminal, the second terminal and the third terminalare arranged one after another in this order at predetermined intervalsin a circumferential direction on an opposite side of an imaginary planethat includes the central axis of the cover end, wherein the oppositeside of the imaginary plane is opposite from another side of theimaginary plane where the discharge conduit is formed; the cover endincludes a plurality of transverse passages, which are formed by aplurality of slide mold parts, while each of the plurality of transversepassages radially communicates a corresponding one of the plurality ofouter passages to an inner passage, which is formed around the tubularportion and is communicated with the discharge passage; and theplurality of transverse passages includes: a first transverse passage,which is formed between the first resin portion, in which the firstterminal is insert molded, and the second resin portion, in which thesecond terminal is insert molded, in the circumferential direction, anda second transverse passage, which is formed between the second resinportion, in which the second terminal is insert molded, and the thirdresin portion, in which the third terminal is insert molded, in thecircumferential direction; and the first transverse passage and thesecond transverse passage together are a V-shape, which diverges in aradially outer direction when viewed in the axial direction; and innersurfaces of the V-shape that bound the second resin portion areconfigured to limit deterioration of a coaxiality of the tubular portioncaused by a deformation at a time of molding.
 2. The liquid pumpaccording to claim 1, wherein the first terminal, the second terminaland the third terminal are arranged at 60 degree intervals about thecentral axis of the cover end.
 3. The liquid pump according to claim 1,wherein the first terminal, the second terminal and the third terminalare respectively made of identical members, which are identical to eachother.
 4. The liquid pump according to claim 1, wherein the firsttransverse passage and the second transverse passage are perpendicularto each other.
 5. The liquid pump according to claim 1, wherein theliquid pump is a fuel pump, which pumps fuel that serves as the liquidand is drawn from a fuel tank.
 6. The liquid pump according to claim 1,wherein: the second resin portion includes a first side surface thatforms the first transverse passage, and includes a second side surfacethat forms the second transverse passage; and the first side surface isperpendicular to the second side surface when viewed in the axialdirection.
 7. A liquid pump configured to pump a liquid, comprising: amotor arrangement that has: a stator, in which a plurality of windingsis wound around cores; and a rotor, which includes a plurality ofmagnetic poles and is configured to rotate about a rotational axis of ashaft by a magnetic field generated at the stator; a housing that isconfigured into a tubular form and receives the stator and the rotor,wherein a plurality of outer passages, each of which passes between aninner wall of the housing and an outer wall of the stator and extendsthrough the motor arrangement in an axial direction, is formed in thehousing; a cover end that is resin molded integrally with one endportion of the stator on one axial side of the motor arrangement andcloses an opening of the housing, wherein: a tubular portion, whichholds a bearing that rotatably supports one end portion of the shaft, isformed along a central axis at a side of the cover end where the motorarrangement is located; a discharge conduit, which has a dischargepassage in an inside of the discharge conduit, is formed at an oppositeside of the cover end, which is opposite from the motor arrangement; anda first terminal, a second terminal and a third terminal, which areconfigured to supply three-phase electric power received from an outsideto the plurality of windings on a phase-by-phase basis, are respectivelyinsert molded in a first resin portion, a second resin portion and athird resin portion of the cover end to seal the first terminal, thesecond terminal and the third terminal from the liquid; and a pumparrangement that includes a rotatable member, which is configured torotate together with the rotor on another axial side of the motorarrangement to pump the liquid, wherein: the first terminal, the secondterminal and the third terminal are arranged one after another in thisorder at predetermined intervals in a circumferential direction on anopposite side of an imaginary plane that includes the central axis ofthe cover end, wherein the opposite side of the imaginary plane isopposite from another side of the imaginary plane where the dischargeconduit is formed; the cover end includes a plurality of transversepassages, which are formed by a plurality of slide mold parts, whileeach of the plurality of transverse passages radially communicates acorresponding one of the plurality of outer passages to an innerpassage, which is formed around the tubular portion and is communicatedwith the discharge passage; and the plurality of transverse passagesincludes: a first transverse passage, which is formed between the firstresin portion, in which the first terminal is insert molded, and thesecond resin portion, in which the second terminal is insert molded, inthe circumferential direction, and a second transverse passage, which isformed between the second resin portion, in which the second terminal isinsert molded, and the third resin portion, in which the third terminalis insert molded, in the circumferential direction; the first transversepassage and the second transverse passage form a V-shape, which divergesin a radially outer direction when viewed in the axial direction; thesecond resin portion includes a first side surface that forms the firsttransverse passage, and includes a second side surface that forms thesecond transverse passage; and the first side surface is perpendicularto the second side surface when viewed in the axial direction.
 8. Theliquid pump according to claim 7, wherein the first terminal, the secondterminal and the third terminal are arranged at 60 degree intervalsabout the central axis of the cover end.
 9. The liquid pump according toclaim 7, wherein the first terminal, the second terminal and the thirdterminal are respectively made of identical members, which are identicalto each other.
 10. The liquid pump according to claim 7, wherein thefirst transverse passage and the second transverse passage areperpendicular to each other.
 11. The liquid pump according to claim 7,wherein the liquid pump is a fuel pump, which pumps fuel that serves asthe liquid and is drawn from a fuel tank.